The median home price in Washington is $590,000. At 80% LTV, the typical loan is $472,000 at the current 6.85% average rate, producing a monthly P+I payment of $3,093. Total interest over 30 years at this rate: $641,416.
Property taxes in Washington average 1.03% of assessed value, or $6,077 per year on the median home. This adds $506/month to your all-in housing cost. When evaluating a refinance, factor in property tax and insurance for a complete picture.
Washington has no state income tax, so there is no state-level mortgage interest deduction. The federal deduction still applies on loans up to $750,000 for itemizers.